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f5d45dc911
The generic memcpy routine provided in kernel does only byte copies. Using word copies we can lower boot time and cycles spend in memcpy quite significantly. Booting on my de0 nano I see boot times go from 7.2 to 5.6 seconds. The avg cycles in memcpy during boot go from 6467 to 1887. I tested several algorithms (see code in previous patch mails) The implementations I tested and avg cycles: - Word Copies + Loop Unrolls + Non Aligned 1882 - Word Copies + Loop Unrolls 1887 - Word Copies 2441 - Byte Copies + Loop Unrolls 6467 - Byte Copies 7600 In the end I ended up going with Word Copies + Loop Unrolls as it provides best tradeoff between simplicity and boot speedups. Signed-off-by: Stafford Horne <shorne@gmail.com> |
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| configs | ||
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| Kconfig | ||
| Makefile | ||
| README.openrisc | ||
| TODO.openrisc | ||
OpenRISC Linux
==============
This is a port of Linux to the OpenRISC class of microprocessors; the initial
target architecture, specifically, is the 32-bit OpenRISC 1000 family (or1k).
For information about OpenRISC processors and ongoing development:
website http://openrisc.io
For more information about Linux on OpenRISC, please contact South Pole AB.
email: info@southpole.se
website: http://southpole.se
http://southpoleconsulting.com
---------------------------------------------------------------------
Build instructions for OpenRISC toolchain and Linux
===================================================
In order to build and run Linux for OpenRISC, you'll need at least a basic
toolchain and, perhaps, the architectural simulator. Steps to get these bits
in place are outlined here.
1) The toolchain can be obtained from openrisc.io. Instructions for building
a toolchain can be found at:
https://github.com/openrisc/tutorials
2) or1ksim (optional)
or1ksim is the architectural simulator which will allow you to actually run
your OpenRISC Linux kernel if you don't have an OpenRISC processor at hand.
git clone https://github.com/openrisc/or1ksim.git
cd or1ksim
./configure --prefix=$OPENRISC_PREFIX
make
make install
3) Linux kernel
Build the kernel as usual
make ARCH=openrisc defconfig
make ARCH=openrisc
4) Run in architectural simulator
Grab the or1ksim platform configuration file (from the or1ksim source) and
together with your freshly built vmlinux, run your kernel with the following
incantation:
sim -f arch/openrisc/or1ksim.cfg vmlinux
---------------------------------------------------------------------
Terminology
===========
In the code, the following particles are used on symbols to limit the scope
to more or less specific processor implementations:
openrisc: the OpenRISC class of processors
or1k: the OpenRISC 1000 family of processors
or1200: the OpenRISC 1200 processor
---------------------------------------------------------------------
History
========
18. 11. 2003 Matjaz Breskvar (phoenix@bsemi.com)
initial port of linux to OpenRISC/or32 architecture.
all the core stuff is implemented and seams usable.
08. 12. 2003 Matjaz Breskvar (phoenix@bsemi.com)
complete change of TLB miss handling.
rewrite of exceptions handling.
fully functional sash-3.6 in default initrd.
a much improved version with changes all around.
10. 04. 2004 Matjaz Breskvar (phoenix@bsemi.com)
alot of bugfixes all over.
ethernet support, functional http and telnet servers.
running many standard linux apps.
26. 06. 2004 Matjaz Breskvar (phoenix@bsemi.com)
port to 2.6.x
30. 11. 2004 Matjaz Breskvar (phoenix@bsemi.com)
lots of bugfixes and enhancments.
added opencores framebuffer driver.
09. 10. 2010 Jonas Bonn (jonas@southpole.se)
major rewrite to bring up to par with upstream Linux 2.6.36